


A Supernatural Case

by Superlocked_25



Series: Supernatural Sherlock [1]
Category: Sherlock (TV), Supernatural
Genre: Crossover, Destiel - Freeform, Engagement, Established Castiel/Dean Winchester, Established Sherlock Holmes/John Watson, Johnlock - Freeform, Mpreg, secret mpreg
Language: English
Status: In-Progress
Published: 2014-03-16
Updated: 2014-03-29
Packaged: 2018-01-15 22:00:11
Rating: Not Rated
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 7
Words: 3,295
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/1320682
Author URL: https://archiveofourown.org/users/Superlocked_25/pseuds/Superlocked_25
Summary: <blockquote class="userstuff">
      <p>This is my first crossover fic, so please comment what you think about it! Sorry if it sucks!</p>
    </blockquote>





	1. Chapter 1

**Author's Note:**

> This is my first crossover fic, so please comment what you think about it! Sorry if it sucks!

John wakes up in Sherlock’s arms and smiles. He and Sherlock have been together for 1 year, and they had been engaged for 1 week. He kisses Sherlock softly to wake him up.

Sherlock stirs slowly and smiles when John pulls away. “Good Morning love.”

“Good Morning.” John says, “Breakfast?”

“Sounds marvelous.” Sherlock says and kisses John’s forehead.

 

They decide to go out for breakfast today, so they go down to Speedy’s. When they walk in Sherlock immediately notices the two men sat in the far corner. He leads John to an open booth near the men and begins to deduce them.

“Hey, who are you deducing this time?” John says. He follows Sherlock’s gaze and see’s the two men. One is really tall and has long hair, while the other is also tall but has short hair and a leather jacket on. The taller one is looking at something on his laptop while the other man looks at a journal. He turns back to Sherlock. “What have you found out?”

“They’re brothers, American, the tallest one is the youngest. They are on their guard constantly, eyes flitting about and always ready to attack, yet they are being calm and sitting in a café to order a meal. They are fighters, I can distinctly see the outline of a gun on each of them. They seem to be researching something, and they are conversing every now and again.” Sherlock tells John.

“That is amazing.” John says with a smile.

Sherlock’s phone rings and he looks at it. “Lestrade, he has a case for us.”

“What is it this time?” John asks.

“Young woman, throat slit but no weapons or prints in the whole house.” Sherlock says.

As they get ready to leave the older of the two men in the corner answers his phone and has a quick conversation before saying loudly. “I found us a job Sammy, now come on.”

“Dean, does there always have to be a job?” the younger man, ‘Sammy’, says.

“Yep, let’s get going. And you’re driving, I’m not cheating on my baby with another car.” The older man, ‘Dean’, says.

Sherlock leaves and John follows after him. As they are on their way to the crime scene, Sherlock can’t help but think about the mysterious men.


	2. Chapter 2

Sam is driving and glances over at Dean. He sees that his brother is absent-mindedly looking at his ring finger. “You miss him then?”

“Hm?” Dean says, looking up.

“Cas, you miss him?” Sam says again.

“Of course I do, but he won’t be getting here for a day or two. He’s not an angel anymore so he has to take a plane, which takes to damn long.” Dean says frustratingly.

“Hey, did you see that guy staring at us at that café?” Sam says, deciding to change the subject.

“Yeah, what about him?” Dean says.

“He got a call right before us and left right before us. You don’t find that a little weird?” Sam asks.

“A little bit, plus that guy was starting to creep me out. The guy he was with looked nice though.” Dean says.

“Yeah, whatever.” Sam says.

“So, tell me about this job again?” Dean says.

“Cassie Jones, age 22, found in her home with her throat slit so deep you could see her spinal cord.” Sam says.

“Gross. Now what makes this our kind of thing?” Deans says.

“The doors and windows were all locked, there were no weapons found, and no fingerprints, let alone any clues. The same thing has happened in the US 10 times and now here 5.” Sam says.

“Ok, so what are we acting as now?” Dean asks.

“I say we go FBI this time, we can always have them call Bobby if they question us.” Sam says.

“Sounds like a plan.” Dean says.

 

They show up at the crime scene dressed in their suits. They walk to the crime scene tape where a curly haired woman is standing.

“Sorry, you can’t go in it’s a crime scene.” The woman says.

Dean nods to Sam and they both pull out their badges. “I’m Agent Smith, this is my partner Agent Wesson. We were sent here to help, we think this might be the same killer as one we’re looking for.”

“Come on.” She says. She leads them over to the body where a salt-and-pepper haired man is talking to another who looks very familiar.


	3. Chapter 3

Sherlock looks over the body and is puzzled. He has no idea who could have killed her, but he is trying to figure it out. That’s when he smells it, sulfur. “Lestrade, why is there sulfur here?”

“Sulfur?” Lestrade repeats.

“Yes sulfur, now whys it here?” Sherlock asks.

“Sir, these two men are from the FBI. They say that they’re here to help.” Donovan says.

Sherlock turns around to see the men from the café this morning, except they are in suits. He sees that both of them tense up. “And you would be?”

“Agent Dean Smith, and my partner Agent Sam Wesson.” Dean says, they both flash their badges. “We think these killings may be the work of a serial killer we’re trying to catch, same MO and everything.”

“Now, have you found any traces of sulfur in the house?” Sam asks.

“Yeah, it’s bloody everywhere.” Lestrade says.

“Do you know why gentlemen?” Sherlock says icily.

John walks up and puts a hand on his arm. “Sherlock, be nice.” He holds out his hand to the taller agent. “John Watson, and this is my fiancé Sherlock Holmes.” He shakes hands with both agents. “Sorry about him, he doesn’t understand what is and isn’t socially acceptable.”

Sam chuckles.

Dean looks at him with raised eyebrows. “What?”

“That sounds a lot like Cas, maybe they have more in common than that.” Sam says.

“Hey, you don’t make fun of Cas at all.” Dean says sternly.

Sam turns to the confused John. “Cas, or rather Castiel, is Dean’s fiancé. He also doesn’t understand what is and isn’t socially acceptable.”

“Castiel…” Sherlock says, thinking. “Isn’t that the name of the angel of Thursday?”

“Yeah, his dad was really religious.” Dean says with a smile, causing Sam to smirk.

“Lestrade, may I have a word with the Agents alone.” Sherlock says.

“No Sherlock, we’re not getting another complaint against you.” Lestrade says.

“Would you like me to tell the whole Yard about your latest lover then?” Sherlock smirks.

Lestrade walks away quickly and leaves John and Sherlock with the Agents.

“Now, you have exactly 60 seconds to explain to me why you’re here impersonating FBI agents. Before I call over Lestrade and have you arrested.” Sherlock says.


	4. Chapter 4

Sam and Dean both tense and glance at each other.

“I don’t know what you’re talking about.” Dean says coolly.

“Oh please I could deduce it easily. Cheap suits, old shoes recently polished, fake IDs, and should I go on and deduce everything about you?” Sherlock says.

“No, I believe that’s enough.” Sam says.

“Look, let us go over this crime scene and we’ll meet you in half an hour in our hotel room. Sound good?” Dean says.

“Yes, and I do expect a full explanation. Just in case though I will be watching you as you examine the crime scene.” Sherlock says.

“Fine, but don’t ask us about anything we say that you don’t understand. You can ask later.” Dean says.

Sherlock and John stand in the doorway as Sam and Dean begin investigating.

Sam kneels next to the body. “Same as the ones in the US and the others here.”

Dean is examining a window and raises two of his fingers. “Sulfur, definitely a demon.”

“But why would a demon do this? It makes the killings look like a serial killer, they usually rip their victims into bits.” Sam says, confused.

“Maybe we’ve found one that likes to have a little fun.” Dean says with a smile. “I mean demons might get tired of doing the same thing every time.”

Sam gives Dean a bitch face before speaking. “We’ll call Bobby, and maybe when Cas gets here he’ll know something.”

“Ok, now time to deal with you two.” Dean says, before turning to face Sherlock and John.

 

They arrive at the motel and all get out of the car. When they enter the room, Dean locks the door behind them.

“Ok, before we talk we need to do a few things.” Dean says, nodding to Sam who pours four glasses of Holy Water. “Drink up!” Dean gulps down a few drinks.

They watch Sherlock and John closely as they both take a tentative sip, and nothing happens.

“Ok, you’re not demons then.” Dean says. He holds out a piece of pure silver. “Now touch this.”

Sherlock and John both do, nothing happens.

“And they’re not shape-shifters.” Sam says.

“What the hell are you talking about?” John says.

“Okay, before we start we should tell you that we’re not crazy. We are going to tell you the complete truth.” Sam says.

Sherlock and John both nod.

“We’re hunters.” Dean says. “We basically hunt down the things nightmares are made out of.” He smiles.

“Nice way to tell them lightly Dean.” Sam says sarcastically.

“Hey, just doing the job.” Dean picks up one of the shotguns from the bag.

John immediately reacts and covers Sherlock.

“Relax, it’s empty. Plus we only have salt rounds.” Dean says as he sits on the edge of his bed and begins to clean the shotgun.

“So, what do you guys hunt?” John asks as he and Sherlock sit down on the chairs.

“Ghosts, demons, shape-shifters, werewolves, vampires, ghouls, you name it and we’ve hunted it.” Dean says.

“How do we know you’re not just crazy?” John asks.

“Ask us any questions, and we’ll answer truthfully.” Sam says.


	5. Chapter 5

Sherlock looks at Sam and begins to deduce. Fidgeting, always constantly moving or focused on something else. Former addict then. “What was it?”

“What?” Sam says.

“What were you addicted to?” Sherlock says.

Sam tenses and looks to the ground.

“Just tell them Sammy, maybe then they’ll believe us entirely.” Dean says.

“Demon Blood.” Sam mutters.

“I’m sorry, did you just say Demon Blood?” John says, stunned.

“Yeah, long story.” Sam rubs the back of his neck.

“I still don’t entirely believe you.” John says.

Suddenly there is a knock at the door. They watch as Dean opens it and smiles. “Cas!” he gathers the smaller man in his arms.

“Hey Dean.” The man, ‘Cas’, gives Dean a soft kiss. “So, did you guys find a new job?”

“Yeah, and now we’re stuck having to explain this to these two guys.” Dean gestures towards Sherlock and John.

“Hey maybe Cas can help us prove our point.” Sam says.

“That’s right. Sherlock, John, let me introduce you to Castiel. My fiancé, and an ex-angel of the lord.” Dean says, one arm around Cas’ waist.

John’s eyes widen and his eyebrows go up in surprise. “You’re an angel?” he exclaims.

“Ex-angel, I fell a year ago.” Cas says.

“So you weren’t named after Castiel the angel of Thursday, you are Castiel.” Sherlock says. He studies Cas, backwards tie, mussed up hair, clearly is confused. But when he stands next to Dean, both of them seem more relaxed and happier.

“Yes, but I am an ex-angel now. I chose to stay on earth.” Cas says.

“Why would you choose earth over heaven?” John exclaims, confused.

Cas glances at Dean. “I already have everything I need to be happy. If I went back I would have to forget about my new family, forget about Dean.”

John smiles at the couple. They are alike him and Sherlock. Cas is confused and doesn’t understand how to deal with people and emotions, and Dean is there to ground him and help him along.

Sherlock starts to deduce Dean. He looks care free, but he can tell in his eyes that he has fought in a great war. They look like John’s did when they first met. “Where did you serve?”

“Excuse me?” Dean says.

“You were in a war, where did you serve?” Sherlock asks.

“You wouldn’t believe me if I told you.” Dean says.

“Try me.” Sherlock says flatly.

“Hell.” Dean says.

John chuckles “Afghanistan felt like hell to, but where did you actually serve?”

“I told you, Hell. I was saved by Cas here.” Dean pulls Cas closer to him and quickly kisses his forehead.

“Wait, you’ve been to Hell?” John exclaims.

“Yeah, now are you convinced that what we’re saying is true? Because we’ve got a demon to gank.” Dean says.


	6. Chapter 6

Dean was stressed, the stupid Brits had been there for an hour. Sammy had started researching and Sherlock and John were helping. He glances at Cas and sees how exhausted and worn down he is. HE walks over to him and speaks quietly. “Hey babe, are you okay?”

Cas shakes his head. “Do you think we can go back to our room?”

“Sure.” Dean helps Cas up. “Sammy we’ll be in our room if you need us, Cas isn’t feeling so well.”

“Alright, feel better Cas.” Sam says.

“Do you want me to check him? I am a Doctor.” John says.

“No, that’s alright. I ate something on the way here that didn’t agree with me.” Cas lies.

 

When they are back in their room, Dean immediately turns to Cas. “You need to remember to sleep babe.”

“I know, this kid is making me exhausted.” Cas says, placing a hand on his stomach.

“We’re going to have to find new excuses soon.” Dean says, sitting behind Cas and also placing a hand on his stomach.

There is a knock on the door. Dean gets up and opens it to find Sherlock standing there. “Do you need us or something?”

“No, may I please come in?” Sherlock asks.

Dean nods and lets him in. “So, why’re you here?”

“To say that I know you lied to us, or at least partially lied.” Sherlock says.

Dean tenses up. “Listen, I don’t know what you’re thinking, but…”

“Castiel is pregnant, isn’t he?” Sherlock says with a smirk.

Cas puts a hand protectively over his stomach. “How did you know?”

“I didn’t know, I saw.” Sherlock says. “Sensitive to smells, and sometimes you would lay your hand protectively over your stomach, like you are now, which has a barely noticeable bulge.”

“Did you tell anyone else?” Dean asks nervously.

“No, I just want to know why you are keeping this a secret.” Sherlock says.

“Because Sammy would freak, it’s not exactly normal.” Dean says. “Plus, our job is dangerous and Cas doesn’t want to stop yet, and Sam would force him to.”

“Your secret is safe with me, but I suggest on telling your brother soon before the bump starts to show more.” Sherlock says, before leaving.

Dean turns to Cas with a small smile. “How about you get some rest? I’ll be to bed in a moment, im going to take a quick shower.”

“Alright.” Cas gives Dean a quick kiss.


	7. Chapter 7

It had taken a week worth of research, and 2 more victims, to finally figure out what the demon’s pattern was.

Cas’s bump was starting to become barely visible, but his trench coat he always wore hid it. But he couldn’t hide the morning sickness, which is the main reason they got a room separate from Sammy this time.

They were now waiting for the demon to show up so that they could kill it.

Suddenly Dean is thrown against one of the walls.

“Dean!” Cas screams.

“Cas! Get out of here!” Dean screams back, before he’s unable talk because of the grip on his throat.

The demon walks into the room with a smile. “So, Team Free Will found some new friends?” he says. “This could have been fun if you didn’t all have anti-possession symbols on you. Way to spoil my fun.”

Sam starts to sneak up behind the demon, while Cas slowly stands up. “Please let him go.” Cas pleads.

“Now why would I do that?” the demon asks with a wicked grin.

Sherlock suddenly notices that a knife is slowly lifting off the ground and pointing towards Cas. “Castiel! Get down!” he jumps in front of Cas, and the blade hits him in the side. He falls to the ground.

Sam sneaks up behind the demon while he’s distracted and stabs him. Dean falls to the floor, and John runs to Sherlock.

“Sherlock! Why did you do that?” John says frantically as he tries to stop the bleeding.

“I called an ambulance they’re on the way now.” Sam says.

“Hang in there love.” John says.

“I’m sorry John, I couldn’t let Castiel get stabbed. He and Dean have a family to take care of.” Sherlock says weakly.

Cas and Dean kneel beside Sherlock. “Thank you, if I had been hit our child wouldn’t have made it. I can never make this up to you.” Cas says.

“As long as you and the child are safe, I couldn’t care less if you made it up to me.” Sherlock says.

The ambulance arrives and the paramedics take him to St. Bart’s.

 

When Dean and Cas see Sam walking over, they get ready for questions.

“What was all that nonsense back there?” Sam says.

“Sammy, we’ve been meaning to tell you…” Dean rubs his hand on the back of his neck.

“Tell me what?” Sam asks, looking between them.

“I’m pregnant.” Cas says.

Sam’s eyes widen and his eyebrows go up in surprise. “So he was telling the truth, about why he took the hit?”

“Yeah, Sherlock found out and promised not to say anything.” Dean says.

“So I’m going to be an uncle?” Sam smiles widely.

Dean and Cas smile. “Yeah, you are.” Dean says.

“Well Congrats to you guys.” Sam says.

“Well at least I can take off my trench coat around you now.” Cas says. He removes the trench coat and the baby bump is immediately noticeable.

“Wow, how far are you along?” Sam asks, stunned.

“A little over 3 months.” Cas says, unconsciously rubbing his belly.

Just then, a man with an umbrella walks into the private waiting area. “Oh, you’re Sherlock’s new acquaintances.” The man says with a blank expression.

“Yeah, now who the hell are you?” Dean says.

“An interested party.” The man says.

“Just leave us alone man.” Sam says.

Suddenly, John opens the door to Sherlock’s room and looks out. “He’s awake, you guys can come on in.” He sees the man and frowns. “He said not to let you in Mycroft.”

“He knows I’ll find out about him eventually.” The man, ‘Mycroft’, says.

“Yeah, you do it your way British Government. He won’t see you now and I doubt he will later.” John says. He turns to Cas, Dean, and Sam. “Please ignore my future brother-in-law. Come on in, he said he wanted to see you guys. Especially Cas, he wants to be certain that you are okay.”

They follow John into the room and Sherlock laying in the hospital bed with a white bandage wrapped around his mid-section.

“Hey there Sherlock, how you doing man?” Dean says, while pulling a chair next to the bed for Cas.

“I’m fine, this isn’t the first time I’ve been here. I’ve even arranged for Molly to bring me some more fingers as a get well soon present when I go home.” Sherlock smiles.

“Fingers?!” Sam exclaims.

John sighs. “You get used to it, I have to live with body parts in the fridge.”

Sherlock rolls his eyes at John then looks to Cas who is seated beside him. “Are you alright?”

“Yes, I am. Thank you once again, I hope I can repay you one day.” Cas says.


End file.
